There’s a couple of ways I’ve experimented with and this version made the roll tightest but I’ve just thought of another way which I’ll use next time:

First off keep a roll of paper backing, have couple of 127 spools and a few bits of sticky tape.
– Cut the exposed end of a 35mm roll flat and tape it to the black back of the 127 paper backing where you tore off the 127 film but try to tape it as straight as you can.
– In a darkroom or changing bag roll the paper backing with a 127 spool tightly by hand towards the taped 35mm film leader and roll on pulling the film out of the canister until you’re at the end of the paper.
– Cut the film and put aside and finish up with a wee bit of tape to hold it together.
– take the other 127 spool and feed the other end into the second spool and start to roll back again looking out for the 35mm film and make sure its fed into the paper.
– once rolled remove the other spool and lightly tape the roll together and keep in a dark place until needed.

Another way I’ve just thought of is to roll using a 127 film camera, that might make it even tighter.